Neutrophilic granulocyte (peripheral blood, human)

Electron microscopy. Two nuclear lobes of the segmented nucleus are visible in a cytoplasm with a moderate amount of organelles but with abundant granules of varying sizes. The motile human neutrophil (9-14 μm) contains at least four types of granules. However, by routine electron microscopy primary and secondary granules only can be discerned. The primary, spherical to ellipsoid granules are (lightmicroscopic) azurophilic granules, and are large (diameter 0.4 μm) (1). They contain e.g. acid hydrolases as acid phosphatase, arylsulfatase, beta glucuronidase, but also myeloperoxidase as an antibacterial substance. The smaller (2) granules are of varying forms(↓: dumb-bell form) and sizes, they are the specific (secondary) granules (diameter 0.2 μm up to length 0.8 μm), they contain substances like lysozyme, phagocytin to be secreted extracellularly involved in mobilization of inflammatory mediators and complement activation. With immuno-electron microscopy a third type of granule (secretion of gelatinases) and a fourth type of granule (so-called phosphasome) with alkaline phosphatase can be discerned.